Size gauging device



Sept. 7, 1948. w. F. ALLER SIZE GAUGING DEVICE Filed April 10, 1946 LNVENTOR My m BY V W 7 Jaw 7 ATTORNEY Patented Sept. 7, 1948 SIZE GAUGINGDEVICE Willis Fay Aller, Dayton, Ohio, ,assignor toi'lhe SheffieldCorporation, Dayton; Ohiopa corporation of Ohio Application'April 10,1946,? Serial No.. 660,901

. 4 Claims.

This invention relates to precision gauging of the size of objects.

One object of the invention is the provision of a precision gaugingapparatus embodying an air leakage gauging nozzle or nozzles cooperatingwith the workpiece or object to be gauged as to size, and. an airpressure controlled electric switch having individually adjustablecontact blades normally biased into exact positions and cooperating withspring blades controlled by a rigid arm secured to the free end of acurved hollow tube that is responsive to changes in air pressure as suchchanges are induced in a size gaugingoperation, the construction beingsuch as to operate with no looseness of construction and with extremepreciseness and freedom from error.

' Another object of the invention is the provision of a-gaugingapparatus of the character mentloned,,in which the pressure tube has anarcuate extent less than 360 degrees and the switch operating arm towhich it isfixed is arranged in the plane of expansive movement of thepressure responsive tube and amplifies the. movement of the tube.

Other objects and advantages of the invention will be apparent from thefollowing. description, the appended claims, and the accompanyingdrawing, in which,

Fig. 1- is aside view, with the [housing or support in central section,of an air pressure controlled electric switch employed in the presentinvention;

Fig. 2 is a sectional View taken on the line 22 of Fig. 1;

Fig. 3 is a detail view showing the pressure responsive tube support andthe indicating mechanism that may be associated with it;

4 is a detail showing the connection-between the indicating pointershaft and the end of the pressure responsive tube and also showing aportion-of the rigid switch operating arm; and

Fig. 5 is a view showing the application of the pressure switch in thesize gauging apparatus of the present invention.

In accordance with the present invention a precision gauging apparatusis provided that checks compares or selects the sizes'of objectsor'parts by measurement of the leakage flow of air supplied underpressure through a gauging nozzle or nozzles cooperating with theobject. The air pressure variations caused by size-differences in theobject gauged as compared to conditions whenan object or standard of theexact or known 2 size is used, are effectiveon a, pressure responsivecurvedtube which in turn-controls adjustable switches that operateelectrical "gauging, measuring or selecting devices.

As shown in the drawing, .in which the same reference numerals .havebeen-used in the several views to designate like pants,v and moreparticularly with reference to Fig.15,"the.-numeral"63 designates a pipeadapted to be connected" to the factory air line, is an adjustablepressure regulator. that. automatically, maintains a selected airpressure supplied to a restriction 65 in a: pipe 65-communi-cating with'a passage Til'in a'gaugingbody' .68. shown as adapted to receivethepa'rt or article 69 to be gaugedas to size. The passage '19 ext-endsto agauging nozzle H the outer surface ofv which is'spaced' slightlyfrom the surface of the object 69, and the space-between the nozzle lland the object -69 determines the amount of leakage-that takes placealong the outer surface of'thenoz'zle. This space isdetermined'lby thesize ofthe object. There are preterably two of these nozzles,- thesecond nozzle 72 being arranged diametrically opposite the-axis ofthe'object 69. "The amount of leakage taking place past the ends-of thegauging-nozzles is thus an accurateindication of thesize or diameterofthe object; and the" amount of this leakage'is measured by the pressureexisting onthe low pressure'side of the restriction 65.

' When an object or master of known size; rrepresenting the maximurnpermissible size in-a tolerance range, is applied to the gauging body 68a certain pressure will exist inthe =pipe-"66. There !Wi11 lbeanotherpressure existing when a master of theminim-um' permissible sizeisapplied. 'When the [obj set to be gauged isapplied, if it is withintolerance requirements, the 'pressure existing in pipefifiwillbe'between the maximum'and minimum pressures determined by themasters.

The lpipeiit is in communication with the end of acurvedpressure-responsive tube which, in turn, controlsa pair ofadjustable precision switches that are connected to electrical gaugingor sizing devices. The tubes and'the switches are arranged in asupportlfl, connected to pipe Sit-by connection 18. r The electricalconnections extending irom the switches are shown at 42 and eachconnected to an electrical relay, is which may be of the electromagneticor electron type. Connection 43. is. a commonreturn Wire.

The support lDisshowna-s a housingin varicusnoperating pants arecontained. .A sheet metal plate i l is secured to the housing bysuitable attaching screws l2, the plate being fastened by means ofscrews it to a supply connection M which forms the support for the fixedend of a curved hollow pressure responsive tube I5 having a free end 85which is annularly movable in response to changes in air pressure towhich the interior of the tube is subjected through the supply pipe E8.The supply pipe is secured to the projecting end of the supplyconnection It by a suitable attachment nut 69.

A short link 2b is fixed to the free end it of the pressure responsivetube and carries a pivot pin 2i which may be connected, as illustratedin Fig. l, to a pointer operating mechanism to give a visible indicationof the pressure, although it should be understood it is quiteunnecessary that 1 such linkage and indicating pointer be used. However,where it is desired to provide a direct reading indicating pointer, thepivot pin 2! is connected through a link 22 to a lever 23 having a pivotsupport at 24 on a mounting plate '25 that is fixed to the supplyconnection M. The other end of the lever 23 is a gear segment havingteeth 26 meshing with a pinion 2'! on the pointer shaft 28. The pointer32 is visible through a glass 2t and operates over a scale plate 39having suitable graduations or markings 3|.

The pressure responsive tube H5, at its free end I6, is securely fixedto a rigid switch operating arm 34, which is preferably brazed orsoldered directly to the outer side of the end portion of the tube, aswill be apparent from Fig. 4, so that the arm 34 lies in and moves inthe plane in which the tube expands and contracts. The tube has a lengthin an annular direction less than 360 degrees so that the integralassemblage constituted by the arm 3 and the tube itself will be quitefirm and have adequate strength to prevent oscillation or looseness ofthe free end of the switch operating arm. This firmness of constructionpermits the gauge to be mounted on a support subjected to vibrationwithout causing oscillatory movements of the contacts. It also is suchthat there can be no looseness of the pointer in a directiontransversethat in which the pointer has normal movement. Theconstruction, however, is such that the free end of the arm 34 has amovement corresponding to the movement of the free end of the tube. butto a considerably amplified degree. This results from the manner inwhich the arm is extended outwardly to a po nt remote from the tube, thearm curving around a portion of the tube and then extendin straightoutwardly but being so arranged that the only place where the arm andthe tube are in contact is at the free end of the tube. where the twoparts are securely fixed together against any relative movement. Theassemblage constituted by the tube and the arm is mechanically frictioness and there is absolutely no lost motion in these parts.

The free end of the arm 3 (see Figs. 1 and 3) is provided with a pair oflugs 36 and 3'! of electrical insulating material such as hard rubber orthe like. The lug 31 operates freely through a hole or slot 38 in arigid switch blade 39 that extends generally parallel to the directionof the free end of arm 34. If the lug 37 extends far enough through thehole in blade 39 it contacts and moves or flexes a flexible metal springstrip or blade M1. The rigid blade 39 and the spring strip 4B areprovided with contact points 4. t! that are normally in contact with oneanother and close the circuit through the two switch blades and throughwires E-Z and 43 that lead to the indicating or controlling device thatis governed by the pressure switch. The spring strip ib has an inherentspring bias that hold it normally in engagement with the blade 39 and,as will be apparent from 1, one end of the spring strip is fixed bymeans of an insulating block 45 to a short spring strip (it that alsocarries the blade 39. One end of the spring strip M3 is fastened to anoutwardly projecting ear i? that is struck up in the metal plate ii, theshort spring strip Alt serving to normally bias both of the switchblades upwardly as viewed in Fig. 1 and holding an insulating lug ie onthe blade 38 yieldingly against the outer end of an adjustment post at.The position of the post 58 can be readily changed by turning thecontrol knob 5i thus rotating a threaded portion 55 of the post 5 withina fixed nut 55" held in the support ill.

At the opposite side of the arm 3& is a similar switch constituted bythe rigid blade 52 having a hole in it through which the lug 36 isfreely movable, and the flexible strip or blade 53 that is normallybiased towards the blade 52 to hold their contact points 58 inengagement. The strip 53 can be moved outwardly by the insulating lug 36when the outer end of the arm 34 is moved upwardly from the positionshown in Fig. l. The ends of the blades 52 an 53 are carried by a shortspring strip E l secured to an ear 55 on plate H. The short spring stripti l normally urges both the switch blades upwardly as viewed in Figs. 1and 3, and hold the rigid blade 52 against an adjustable post 56controlled by adjustment ltnob 5?. The adjustment post '56 extendsfreely through a hole in the flexible blade 53 and engages an insulatinglug 58 on the rigid blade 52.

The two adjustment knobs 5i and 5'? can be so turned as to locate thetwo pairs of switch blades free of the ends of the insulating lugs 36and 3'! so that both switches will be closed when the arm 36 is in acentered position as illustrated in Fig. 1, which is a position itassumes when there is some air pressure existing in the interior of thetube. With atmospheric pressure in the tube, the tube will be contractedand the outer end of the arm 34 will move downwardly and engage theflexible spring strip 49 so as to move it out of contact with the rigidblade 39. As the pressure in the tube increases to some predeterminedvalue, and the tube expands it will move the arm 34 upwardly and closethe circuit of the switch blades 39 and it]. It may then travel furtherthrough a distance controlled by the setting of the knob 57 before thelug 36 engages and opens the switch blade 53 from the rigid blade 52.The amount of motion required of the arm 3 before closing one switch andopening the other can be made as great or as small as desired merely bycontrolling the position of the knobs 5! and 51.

When a part of standard or known siZe is applied to the body 68, theknobs 5i and 57 are set so that objects that fall within the acceptablerange of sizes will not cause either of the two switches to open. Thuswhen the object to be tested is in place in the body 68, one or theother of the two switches will be opened if the size of the object iseither too large or too small. These switches control the relay coils orelectron tubes which are suitably connected to electrically energizeddevices such. asuselector 'gateszor, indicators.

Although-the:insulating-knobs? and 31 are required to: -pass..through1110165 in. .one. of the switch; blades of. each-pain-of switches, theseholes need lonlybe .made slightly largertharr .the size-of the.insulatinglugs sinceno lost motion can be. present .ins..the switclrblades; themselves and. no freedom .of movement is ipermitted the arm 34in: a: direction. transverse to .that .-in-;wh-ich it -is normally;zmovablegior? in. other words: in; a plane transversento the movement;of:.:the :pressure responsive tube itself.

Noundue strains. are applied either to the tube, the arm 34, or theswitch blades, such as would interfere with the-proper setting andoperation of the: apparatus, when the arm is moved excessively in onedirection or-the other due to unusually largepressure or due tqzeropressure existing in the tube. *Thismovement-cannot effeet the; settingof the rigid-spring blades of the switches and imposes no unus ual.forces; onathe op r tin :parts ,of t r;m chanism. sinc 1 the flexibl prn blade can yi l o rd to a very considerable degree; and-will; promptlyreturn to full contact with the rigid blades when the moving force isremoved. The switch contacts operate in a precise manner so as to makeor break contact at an exact position of the arm with a precision of afractional part of a. ten thousandth of an inch movement of the flexiblecontact. The fixed switch blade arrangement is such that the fixedcontact does not yield or move when the pressure of the flexible bladeis applied to it or removed from it, and regardless of the extent offlexing movement of the flexible blade it will return to bring itscontact point into contact with the adjustably fixed blade under the airpressure condition for which the device is set.

The electrical circuit controlled by the switch blades 39 and 40 isthrough the wires 42 and 43, while switch blades 53 and 52 are connectedrespectively to a wire 60 and to an extension SI of wire 42, all theswitches and wires being insulated from the tube and the arm 34 so thatno current flow through the tube can take place and inaccuracies ofindications due to heating or inductive effect on the tube arecompletely avoided.

With an air pressure switch of this character the automatic operation ofair pressure controlled sizing devices can be effected with precisionsince any particular pressure that may be applied to the pressureresponsive tube I5 will always result in exactly the same position ofthe switches for any initial setup, and precision comparison readingsobtained in a device using a supply pressure of the order of twentypounds per square inch that will show size variations smaller than athousandth of an inch and, if desired, to show size variations evensmaller than one ten-thousandths of an inch. In such a precision sizingextremely reliable operation is necessary and the pressure controlledswitches must be necessarily such that the arrangement can be used onvibrating parts, be applied in any of several positions, and be capableof operation over long periods of time without attention, otherwise theemployment of a pressure switch in a size gauging system that employsair leakage as a basis for size measurement would be impractical. It isof utmost importance that the device should repeat time after time Withexactness and precision capable to distinguish size difierentials of theorder of a part of a thousandth of an inch.

The.pnesentint nt on.accomplish s..these'des ble results.

.J'WhiIe th fen nofs app rat aher inzdeseri e constitutes; a: preferreda embodiment; of the: inventi n, it ;is, to bezunderstood thatthelinvention is;not;li mited to thisgprecise form of apparatus,and-that bans sx xbe :inade therein withou ep rtin fzfmm t e co f. thevention :Which iszdefin dzin th appende cla m What 5 la me is I 1.iIn-agprecisionr. gau ing app rat s for n ing-the sizeof an object; by:measuring the amount of. air. leaka supplie un er. pre su thr h agauging noz l or nozzl cooperatin wi h h object: in combination; a gauin noz l f rcooperationwith the object tube. gauged-a pressureresponsivecurved tube having a fixed end; and having. aclosed ;,freeendwhich :has expansive movement .-in-, a 'plane in accordance with.pressure changes; a support; for the ifixed, end of said tube.meansplaoingthefixed endof said tube in com municationwith saidmozzlegarigid armfixedly secured: atone endsthereof; ,to the free end;- ofthetube. and :proj ectingwf-rom the tube to ;a remote location; so theremote endof the; arm-moves in accordance with the:movementrof the.freeendwf the tube, a rigid switch blade at each side of said arm, aflexible spring blade at each side of said arm biased to contact withits respective rigid blade and movable from its respective rigid bladeby said arm, means fixed with respect to said support for carrying saidblades, and means for independently adjustably setting said rigid bladesto precisely located positions.

2. In a precision gauging apparatus for gauging the size of an object bymeasuring the amount of air leakage supplied under pressure through agauging nozzle or nozzles cooperating with the object, in combination, agauging nozzle for cooperation with the object to be gauged, a pressureresponsive curved tube having a fixed end and having a closed free endwhich has expansive movement in a plane in accordance with pressurechanges, a support for the fixed end of said tube, means placing thefixed end of said tube in communication with said nozzle, a rigid armfixedly secured at one end thereof to the free end of the tube andprojecting in the plane of expansive movement of the tube to a locationremote from the tube so the remote end of the-arm moves in accordancewith the movement of the free end of the tube but to an amplifieddegree, a rigid switch blade at one side of said arm, a flexible springblade biased to contact with the rigid blade and movable from the rigidblade by said arm, means fixed with respect to said support for carryingsaid blades. means for adjusting the position of said rigid blade to aprecisely located position, and an electrical relay connected to saidblades and electrically independent of said tube.

3. In a precision gauging apparatus for gauging the size of an object bymeasuring the amount of air leakage supplied under pressure through agauging nozzle or nozzles cooperating with the object, in combination, agauging nozzle for cooperation with the object to be gauged, a pressureresponsive curved tube having a fixed end and having a closed free endwhich has expansive movement in a plane in accordance with pressurechanges, a support for the fixed end of said tube, means placing thefixed end of said tube in communication with said nozzle, a rigid armfixedly secured at one end thereof to the free end of the tube andprojecting in the plane of expansive movement of the tube to a locationremote from the tube so the remote end of the arm moves in accordancewith the movement of the free end of the tube but to an amplifieddegree, an insulating lug near the outer end of the arm, a perforatedrigid switch blade through which the lug is freely movable, a flexiblespring blade biased to contact with the rigid blade and movable from therigid blade by said lug, means fixed with respect to said support forcarrying said blades, and means for adjustably setting the position ofsaid rigid blade to a precisely located position.

4. In a precision gauging apparatus for gauging the size of an object bymeasuring the amount of air leakage supplied under pressure through agauging nozzle or nozzles cooperating with the object, in combination, agauging nozzle for cooperation with the object to be gauged, a pressureresponsive curved tube having a fixed end and having a closed free endwhich has expansive movement in a plane in accordance with pressurechanges, a support for the fixed end of said tube, means placing thefixed end of said tube in communication with said nozzle, the tubehaving an annular extent less than 360, a rigid arm fixedly secured atone end thereof to the free end of the tube and projecting in the 8plane of expansive movement of the tube to a location remote from thetube so the remote end of the arm moves in accordance with the movementof the free end of the tube, a lug at each side of the outer end of thearm, a pair of perforated rigid switch blades one at each side of saidarm through which the lugs are .freely movable. a flexible spring bladebiased to contact with each rigid blade and movable from the rigid bladeby said lugs, means fixed with respect to said support for carrying saidblades, and means for independently adjusting the position of each ofsaid rigid blades.

WILLIS FAY AILER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

